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TUCoPS :: Crypto :: ciack070.htm

PGP Additional Decryption Keys (ADKs) Vulnerability
PGP Additional Decryption Keys (ADKs) Vulnerability Privacy and Legal Notice


K-070: PGP Additional Decryption Keys (ADKs) Vulnerability

August 28, 2000 16:00 GMT
PROBLEM:       An implementation flaw allows unsigned Additional Decryption
               Keys (ADKs) to be added to a certificate and used for
PLATFORM:      Those running PGP versions 5.5.x through 6.5.3, both domestic
               and international.
DAMAGE:        The attacker who inserted the unsigned ADK can decrypt messages
               that were later encrypted using the altered certificate.
SOLUTION:      It is up to the sender to verify that the certificate that is
               used for encryption does not contain any unsigned ADKs. Network
               Associates, Inc. has released many product updates and HotFixes
               for this problem. Apply the appropriate update and/or HotFix.

VULNERABILITY The risk is MEDIUM. The vulnerability is difficult to exploit. ASSESSMENT:
[ Start Network Associates, Inc. Advisory ] PGP ADK Security Advisory On the morning of Thursday, August 24, researchers in Germany announced the discovery of a bug in PGP versions 5.5 through 6.5.3, regarding how those versions handle unauthorized Additional Decryption Key (ADK) additions to the unhashed/unsigned areas of PGP keys. This page provides the most up-to-date information regarding this issue and what steps Network Associates is taking. Please refer back to this page in the future for updates. As reported in the CERT advisory, exploitation of this bug is unlikely due to the unique circumstances under which an attack could be launched. To date, there have been no reported exploits. WHAT'S NEW Network Associates performed a thorough inspection of the world's largest public PGP keyserver (, containing nearly 1.2 million PGP keys, and found that no keys contained on the server were affected by this issue. A software update has been applied to and which automatically cleanses keys as they are uploaded to the servers. The cleansing process removes any signatures that have been tampered with (containing offending unhashed subpackets). A HotFix for PGP Certificate Server customers will be released soon that contains this update. Network Associates strongly recommends that customers download and install this HotFix on their PGP Certificate Servers as soon as it is available. We have released a new command line utility, PGPrepair 1.0, that will scan PGP keyrings and look for (and can repair) keys that have been tampered with. This utility is available on Windows, Solaris and Linux platforms. The PGPrepair tool is designed to repair keyrings created and/or used by PGP versions 2.6.2 and above. It can be applied to personal keyrings or to large keyserver keyrings (including PGP Certificate Servers). We have also released many product updates and HotFixes which resolve this issue. For more information about which versions of PGP are affected by this issue, what product updates/HotFixes are available and what we recommend you do regarding this issue, please visit the PGP Product Information Center for the ADK Security-Related Bug. Network Associates/PGP Security plans to release a detailed, formal advisory about this issue in the near future. (C) 2000, Network Associates, Inc. and its affiliated Companies. All Rights Reserved. [ End Network Associates, Inc. Advisory ]

CIAC wishes to acknowledge the contributions of Network Associates, Inc. for the information contained in this bulletin.
CIAC services are available to DOE, DOE Contractors, and the NIH. CIAC can be contacted at:
    Voice:          +1 925-422-8193 (7 x 24)
    FAX:            +1 925-423-8002
    STU-III:        +1 925-423-2604
    World Wide Web:
                     (same machine -- either one will work)
    Anonymous FTP:
                     (same machine -- either one will work)

This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes.
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